// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.EntityFrameworkCore.Metadata.Internal;

namespace Microsoft.EntityFrameworkCore.ChangeTracking.Internal;

/// <summary>
///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
///     the same compatibility standards as public APIs. It may be changed or removed without notice in
///     any release. You should only use it directly in your code with extreme caution and knowing that
///     doing so can result in application failures when updating to a new Entity Framework Core release.
/// </summary>
public class DependentKeyValueFactoryFactory
{
    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual IDependentKeyValueFactory<TKey> Create<TKey>(IForeignKey foreignKey)
        => foreignKey.Properties.Count == 1
            ? CreateSimple<TKey>(foreignKey)
            : (IDependentKeyValueFactory<TKey>)CreateComposite(foreignKey);

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual IDependentKeyValueFactory<TKey> CreateSimple<TKey>(IForeignKey foreignKey)
    {
        var dependentProperty = foreignKey.Properties.Single();
        var principalType = foreignKey.PrincipalKey.Properties.Single().ClrType;
        var propertyAccessors = dependentProperty.GetPropertyAccessors();

        if (dependentProperty.ClrType.IsNullableType()
            && principalType.IsNullableType())
        {
            return new SimpleFullyNullableDependentKeyValueFactory<TKey>(dependentProperty, propertyAccessors);
        }

        if (dependentProperty.ClrType.IsNullableType())
        {
            return (IDependentKeyValueFactory<TKey>)Activator.CreateInstance(
                typeof(SimpleNullableDependentKeyValueFactory<>).MakeGenericType(
                    typeof(TKey)), dependentProperty, propertyAccessors)!;
        }

        return principalType.IsNullableType()
            ? (IDependentKeyValueFactory<TKey>)Activator.CreateInstance(
                typeof(SimpleNullablePrincipalDependentKeyValueFactory<,>).MakeGenericType(
                    typeof(TKey), typeof(TKey).UnwrapNullableType()), dependentProperty, propertyAccessors)!
            : new SimpleNonNullableDependentKeyValueFactory<TKey>(dependentProperty, propertyAccessors);
    }

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual IDependentKeyValueFactory<object[]> CreateComposite(IForeignKey foreignKey)
        => new CompositeValueFactory(foreignKey.Properties);
}
